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In quantum computation, quantum coherence must be maintained during gate operation. However, in physical implementations, various couplings with the environment are unavoidable and can lead to a dephasing of a quantum bit(qubit). The…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Toshifumi Itakura , Yasuhiro Tokura

In the framework of nuclear magnetic resonance, we consider the general problem of the coherent control of a spin coupled to a bath by means of composite or continuous pulses of duration $\tau_\mathrm{p}$. We show explicity that it is…

Quantum Physics · Physics 2010-03-16 S. Pasini , P. Karbach , C. Raas , G. S. Uhrig

The qubit (or a system of two quantum dots) has become a standard paradigm for studying quantum information processes. Our focus is Decoherence due to interaction of the qubit with its environment, leading to noise. We consider quantum…

Mesoscale and Nanoscale Physics · Physics 2015-05-27 Ebad Kamil , Sushanta Dattagupta

We investigate in detail, using both analytical and numerical tools, the decoherence of electron spins in quantum dots (QDs) coupled to a bath of nuclear spins in magnetic fields or with various initial bath polarizations, focusing on the…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Wenxian Zhang , V. V. Dobrovitski , K. A. Al-Hassanieh , E. Dagotto , B. N. Harmon

We experimentally demonstrate a robust dynamical decoupling protocol with bounded controls using long soft pulses, eliminating a challenging requirement of strong control pulses in conventional implementations. This protocol is accomplished…

Quantum Physics · Physics 2016-09-28 F. Wang , C. Zu , L. He , W. -B. Wang , W. -G. Zhang , L. -M. Duan

Long-lived optical quantum memories are of great importance for scalable distribution of entanglement over remote networks (e.g. quantum repeaters). Long-lived storage generally relies on storing the optical states as spin excitations since…

Quantum Physics · Physics 2017-08-15 Emmanuel Zambrini Cruzeiro , Florian Fröwis , Nuala Timoney , Mikael Afzelius

Dynamical decoupling as a quantum control strategy aims at suppressing quantum decoherence adopting the popular philosophy that the disorder in the unitary evolution of the open quantum system caused by environmental noises should be…

Quantum Physics · Physics 2018-01-17 Jun Jing , Ting Yu , Chi-Hang Lam , J. Q. You , Lian-Ao Wu

In the NISQ era, where quantum information processing is hindered by the decoherence and dissipation of elementary quantum systems, developing new protocols to extend the lifetime of quantum states is of considerable practical and…

Quantum Physics · Physics 2025-03-12 Colin Read , Eduardo Serrano-Ensástiga , John Martin

We have studied decoherence in a system where two Josephson-junction flux qubits share a part of their superconducting loops and are inductively coupled. By tuning the flux bias condition, we control the sensitivities of the energy levels…

Superconductivity · Physics 2010-07-08 Fumiki Yoshihara , Yasunobu Nakamura , Jaw-Shen Tsai

In this paper we investigate the short-time decoherence from Ohmic and 1/f noise of single Josephson charge qubit (JCQ). At first, we use the short-time approximation to obtain the dynamics of the open JCQ. Then we calculate the decoherence…

Quantum Physics · Physics 2009-11-11 Xian-Ting Liang

Quantum annealing is a method to solve optimization problems that leverages quantum tunneling in a coupled qubit system. We present a detailed study of the coherence of a tunable capacitively-shunted flux qubit, designed for coherent…

Dynamical decoupling (DD) is a popular technique for protecting qubits from the environment. However, unless special care is taken, experimental errors in the control pulses used in this technique can destroy the quantum information instead…

Quantum Physics · Physics 2011-06-20 Alexandre M. Souza , Gonzalo A. Alvarez , Dieter Suter

Within quantum information frameworks, managing decoherence stands as a pivotal task. The present work delves into decoherence dynamics of a dressed qubit, represented by a spinless fermion hopping between two lattice sites that are…

Quantum Physics · Physics 2025-01-03 Saima Bashir , Muzaffar Qadir Lone , Prince A Ganai

We study the entanglement dynamics and relaxation properties of a system of two interacting qubits in the two cases (I) two independent bosonic baths and (II) one common bath, at temperature T. The entanglement dynamics is studied in terms…

Quantum Physics · Physics 2017-05-10 G. Campagnano , A. Hamma , U. Weiss

The effects of a collection of classical two-level charge fluctuators on the coherence of a dynamically-decoupled qubit are studied. Distinct dynamics are found at different qubit working positions. Exact analytical formulae are derived at…

Mesoscale and Nanoscale Physics · Physics 2015-10-21 Guy Ramon

Progress in fabrication of semiconductor and superconductor qubits has greatly diminished the number of decohering defects, thus decreasing the devastating low-frequency $1/f$ noise and extending the qubits' coherence times (dephasing time…

Mesoscale and Nanoscale Physics · Physics 2024-08-23 M. Mehmandoost , V. V. Dobrovitski

Refocusing, or dynamical decoupling, is a coherent control technique where the internal dynamics of a quantum system is effectively averaged out by an application of specially designed driving fields. The method has originated in nuclear…

Quantum Physics · Physics 2007-06-05 Leonid P. Pryadko , Gregory Quiroz

Even though the traditional dynamical decoupling methods have the ability to resist dynamic dephasing caused by low frequency noise, they are not appropriate for suppressing the residual geometric dephasing, which arises from the…

Quantum Physics · Physics 2017-03-17 Xiao-Ke Qin , Guang-Can Guo , Zheng-Wei Zhou

We suggest and demonstrate a protocol which suppresses dephasing due to the low-frequency noise by qubit motion, i.e., transfer of the logical qubit of information in a system of $n \geq 2$ physical qubits. The protocol requires only the…

Mesoscale and Nanoscale Physics · Physics 2016-01-13 D. V. Averin , K. Xu , Y. P. Zhong , C. Song , H. Wang , Siyuan Han

Decoherence in superconducting qubits is known to arise because of a variety of environmental degrees of freedom. In this article, we focus on the influence of thermal fluctuations in a weakly damped circuit resonance coupled to the qubit.…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 P. Bertet , I. Chiorescu , C. J. P. M Harmans , J. E. Mooij